The present invention relates to an injector device for containers having an opening with or for an injection needle, the container optionally being of syringe type with a bagel of axially roughly constant cross-section, the opening for the needle being arranged at the barrel front and at least one movable wall, optionally with a piston rod connected thereto, inserted in the barrel, the injector for the containers comprising a) a housing, b) a seat or carrier, arranged for reception of the needle or container and for allowing movement thereof, in relation to the housing, in the axial direction between a rear, needle-covering, position and a forward, needle-exposing, position, c) a penetration arrangement operable to move the needle from the rear position to the forward position, d) optionally a return arrangement operable at least to move the needle in the rearward direction, e) an injection arrangement operable at least to expel container content through the needle and f) at least one control button arranged on the housing and operable to at least initiate operation of the penetration arrangement and/or the injection arrangement.
Although simple in principle injection procedures based on syringe type devices with injection needles require mastering of several discrete steps. Before the mere injection procedure some initiation actions may be required. Filling the syringe with medication withdrawn from a reservoir such as a vial may be needed, taking into account the proper dose to be administered. In order to avoid this step in the actual treatment situation it is common to provide pre-filled syringes, in which case, however, a dose setting or selecting step may be needed. In its first movement the syringe piston may need an extraordinary break-loose force after storage to overcome both internal reshaping resistance and an increased wall friction due to adherence or depletion of lubricant in contact points. For storage and shelf life reasons pre-filled syringes sometimes are delivered in dual or multiple-chamber form, requiring an additional mixing step immediately before treatment. De-aeration and pre-ejection are generally needed to remove gas in the vessel compartment and fill out spaces for example at the front sealing, outlet attachments and the interior of the outlet devices or needles. The injection procedure proper can be said to involve the basic steps of penetrating the skin with the needle, performing the injection of the medical preparation and withdrawal of the needle from the tissue. The target tissue may differ in e.g. subcutaneous, intramuscular, intracavernosal or intravenous injection and require somewhat different injection techniques, including aspiration steps. Typical problems are full needle penetration into the desired target tissue, injection only after proper location of the needle and full injection of the prescribed dose before the needle is retracted. After injection it is nowadays common to shield or destroy at least the needle to avoid infection transmission by inadvertent secondary needle pricks.
These demands can be met also when using the simplest injection devices, such as the common hypodermic syringe, when in the hands of a skilled operator who also may initiate medically relevant corrective measures in case of accidents and malfunction. However, a general treatment trend is to place administration responsibility on the patients themselves, also in the case of child, elderly and disabled persons. In long-term treatment the patient often develop a certain skill but less frequent administration schemes also exist, often including situations of emergency or patient imbalance. Other unique problems in patient selfadministration, as compared to assistant operated administration, is that less suitable and often strained body positions are required and that apprehended or experienced pain or discomfort may interfere with the medically desirable action pattern. In summary, especially the selfadministration requires more sophisticated devices to facilitate the injection procedure and avoid or reduce risks for mistakes. Patients dependent on daily or occasional administrations also have a legitimate need for convenience and devices discrete enough to be brought around in daily life. Yet it is desirable that such sophistication and convenience is kept simple and inexpensive to allow for widespread distribution and inclusion also in disposable devices.
More or less automated devices has since long existed to enable laymen with limited training performing injections with reasonable safety in critical or emergency situations or to provide an option for patients fearing the needle insertion step. Mechanical automation is provided in common autoinjectors. Typically the user is expected to position the device in proper injection orientation against the skin and operate a trigger button. Stored mechanical energy, e.g. in a spring system, may then perform autopenetration into the tissue, autoinjection of the medical and possibly also automatic needle retraction. Simpler systems may not provide autopenetration but assume the user to make the needle insertion. Generally, once triggering has occurred, either intentionally or inadvertently, the operation sequence proceeds irreversibly. Moreover, the dislocation risks are generally high in mechanical devices due to rebound effects and the forced transitions involved, especially as the forces released may have to be dimensioned for the highest foreseeable operation resistance. Besides being expensive and ungainly, these devices rarely give the patient the experience of full control of the injection procedure and the possibility to halt or correct the injection procedure in case of pain or discomfort.
Automated devices based on electronic or electromechanical principles have also been proposed. The known devices may take advantage of automation principles in several respects, such as the precise and reproducible injection possible with electric motors, motor assisted autopenetration and mixing or reconstitution, cartridge identification, sample analysis, injection data collection and manipulation, dose setting, injector orientation relative gravity for proper mixing or de-aeration etc. Certainly this diversity of possibilities make the automated devices in this class useful in many situations, especially for repeated and frequent use, although the devices tend to be too expensive for broad or disposable use. Again, for patients in favor of personal control the automated functions may be adversely experienced.
On the contrary, simpler manual devices may not at all provide the ergonomic, convenience and safety requirements outlined. A syringe type device for example gives no or little assistance in respect of initiating steps, needle penetration or retraction and requires a cumbersome reverse grip for injection on many body sites and offers no safe sequencing of the various steps involved. Numerous so called xe2x80x9cinjection pensxe2x80x9d have been proposed and marketed, mainly for repeated and regular self-administration, e.g. of insulin or growth hormone, in which multi-dose ampoules are inserted and pre-selected doses delivered, typically by manipulation of an end button. These devices are designed for ease of use in everyday life and facilitate repeated dosing bat do not cure the other problems associated with hypodermic syringes. Also known are injection devices with alternative positioning of control buttons for injection For example, the patent specifications U.S. Pat. Nos. 4,444,560, 4,581,022 and 4,820,287 and WO 96/17640 all disclose a lateral lever with a link arrangement to a piston rod, mainly for the purpose of amplifying the expulsion pressure on viscous dental pastes. Pistol type grips with link arrangements for injection are also known, as exemplified by FR 2717697, mainly for ease of gripping instruments for veterinary mass injection. Also known, as exemplified by FR 2586192, are lateral releasable wheels for fine-tuned movements of needle instruments, mainly for laboratory work. All these solutions, however, are not intended for self-administration and are not optimized for such purposes. For example, no solutions are provided for controlled movement of both the needle and the injection mechanism. Simple devices with means for needle movement as well as injection movements are known, as exemplified by U.S. Pat. Nos. 5,425,722 and 5,147,323, but again without consideration to self-administration, e.g. by requiring different grips for the two actions and without securing proper sequencing.
Accordingly there is a continuing need for simple and inexpensive injection devices able to assist the user in the various handling steps involved, preventing or ameliorating mistakes and offering an ergonomic, convenient and non-traumatic product, especially useful for patients under self-administration. Although the present invention may have a more general utility, it will mainly be described against this background.
A main object of the present invention is to avoid the disadvantages of known injection devices as described. A more specific object is to provide an injection device able to perform both a needle penetration and an injection step and possibly also a needle retraction step. Another object is to provide a device dependent mainly only on manual energy for operation. Still another object is to provide a device assisting in the initiation steps preceding the injection procedure. Yet another object is to assist in securing a proper injection sequence. A further object is to provide a device able to give amplified or adapted force in various operation phases. Yet another object is to provide a device suitable for delivery of varying doses. Another object is to provide a device compatible with pre-filled syringes of various natures. Still another object is to provide a device suitable for self-administration. A further object is to provide a device ergonomic in use and convenient to handle. Yet another object is to provide a device allowing for minimum pain or discomfort in use. Still another object is to provide a device giving the user control over the injection procedure, yet with maintained safety. Another object is to provide a simple device of low cost, usable as a disposable device. A further object is to provide methods for operating the devices as described.
These objects are reached with the device and method having the characteristics set forth in the appended claims.
By use of an externally accessible control button linked to the device mechanism in such a manner as to allow the operation of the various phases with manual force applied to the button the overall mechanical design can be kept simple and inexpensive. Making at least part of the mechanism movements in the phases at least partially a function of control button position, the patient is given a feed-back from the actions taken, enabling corrective measures. If for example penetration of the needle through the skin causes pain it is possible to slow down needle insertion, halt the operation or select a new target site. Similarly if pain is experienced from the injection phase the injection speed can be reduced, halted or made intermittent. If the phase movements are reversibly dependent of control button position the cause of discomfort can be fully reversed e.g. allowing under the penetration phase partial or fill needle retraction for correction or postponement of the injection procedure. During the injection phase reversal may allow for example aspiration in intravenous injection. Use of the same control button for both the penetration step and the injection step allows the user to perform complete these phases without grip change, allows use of one hand only, reduces the risk for pain caused by grip change dislocation or rocking and eliminates the cause of improper sequencing through inadvertent operation of the wrong control element or double activation of multiple controls. These advantages are consistent with repeated use and operation of the same control button for the various phases. Such an arrangement additionally serves to give the patient tactile feed-back from the progress and completion of phases, thereby increasing patient control and reducing mistake risks. Furthermore it facilitates mechanical transition between phases and functional adaptations to each phase requirement, e.g. allowing different gear ratios between phases or varying response characteristics within a phase. It also facilitates arrangement of simple mechanical lock and release means for mandatory or non-reversible steps in the procedure chain. Mandatory process steps, complementary to patient controlled steps, serve to assist the user in avoiding hazardous sequencing mistakes and to secure proper completion of a phase before the next is enabled and also serve to train and accustom by guidance an inexperienced user to the expected injection program. It has been found beneficial, especially for self-administration purposes, to devise the control button so as to move when operated at least partially in a perpendicular direction with respect to the needle axis, rather than in a coaxial manner and preferably with a side or lateral position relative to the device housing. The control button will be accessible for compression also by the palm, not only by a finger, resulting in a more stable activation with one or two hands, advantages of general importance to avoid no pain but also of particular importance for patients with reduced hand strength or mobility. Furthermore, the device can be held in the palm equally efficient with the needle pointing forwards or rearwards, broadening the operation range and rendering the device equally useful for patient and assistant use. A control button movement different from the penetration direction reduces the risks for any involuntary phase triggering in the preparative actions when the device is pressed against the skin. For a given ampoule length the arrangement also allows for an overall shorter and more handy device. The general design principles outlined are fully compatible with common single or multiple chamber ampoule types in unfilled or pre-filled form and their required initiation steps. If desired the device can include a dose setting arrangement simply by limiting piston stroke length. A needle retraction capability for increased post-injection safety easily flows from a slight modification of the penetration mechanism. All device features can be realized with low cost means permitting its use for most medical purposes including single shot disposable applications.
Further objects and advantages of the invention will be evident from the detailed description hereinbelow.
In the absence of explicit statements to the contrary, as used herein expressions like xe2x80x9ccomprisingxe2x80x9d, xe2x80x9cincludingxe2x80x9d, xe2x80x9chavingxe2x80x9d, xe2x80x9cwithxe2x80x9d and similar terminology shall not be understood to be exclusively restricted to recited element but shall be understood to allow for the presence of further elements as well and shall be understood to cover any element in integral, subdivided or aggregate forms. Similarly, expressions like xe2x80x9cconnectedxe2x80x9d, xe2x80x9cattachedxe2x80x9d, xe2x80x9carrangedxe2x80x9d, xe2x80x9cappliedxe2x80x9d, xe2x80x9cbetweenxe2x80x9d and similar terminology shall not be understood to cover exclusively direct contact between the recited elements but shall be understood to allow for the presence of one or several intervening elements or structures. The same applies for similar expressions when used for description of forces and actions.
Also as used herein the concept xe2x80x9cmanualxe2x80x9d in connection with force or energy applied to the controls of the device shall be understood to mean that the operator applies, directly or indirectly, the force or energy in a manner controlling the procedure under consideration. It shall be understood to include servo arrangements in which force or energy from another source than the operator, e.g. stored energy in a spring or gas or supplied energy, is used in full or in part in assisting driving of the procedure as long as action of the operator determines the proceeding, although servo assistance is mostly not needed or preferred. In contrast to a xe2x80x9ctriggerxe2x80x9d action, which may be an on/off action, the manual action bears, at least partly or over a limited range, a function relationship to position in the procedure affected.
The injector described herein may be used for a variety of purposes within and beyond the medical area and for any type of preparations, such as chemicals, compositions or mixtures, in any container and delivered for any purpose. For reasons outlined the system has certain special values in connection with medical delivery devices where also the design constraints are more severe than in most other applications. For convenience the invention will be described in terms of this application.
Normally the material to be delivered is a fluid and preferably a liquid, including materials behaving as liquids such as emulsions or suspensions. These observations relates to the final preparation whereas other components, notably solids, may be present before final preparation. The nature of container content shall also be understood to include medical in broad terms and to embrace for example natural components and body fluids pre-filled or drawn into the container although most commonly the medical is factory prepared.
The containers usable in the present injectors generally comprises a container for the preparation and an opening through which the preparation can be delivered and a broad range of container types are useful. A needle, cannula or a similar penetration device, all referred to as xe2x80x9cneedlexe2x80x9d herein, should be in fluid connection with the opening, e.g. by being arranged on, at or with a conduit to the opening Unless a container type in itself includes means for ejecting its content a pimp mechanism may additionally be needed to be further explained. Syringe type containers are preferred for use in the present injector and shall be understood in broad terms and can generally be said to include a barrel having a front part and a rear part defining a general axis, an outlet for the preparation, typically comprising a liquid in broad sense, arranged at the front part and at least one movable wall arranged at the rear part, a displacement of which wall causes the preparation to be moved towards or expelled through the outlet, thereby including an inherent pump mechanism. Barrel shape and movable wall have to be mutually adapted. The barrel of for example glass or plastic may have a substantially constant internal cross-section, with a similarly constant barrel axis, between front and rear pails giving a generally tube-shaped barrel, and most preferably the cross-section is of the common circular type giving a substantially cylindrical barrel. The movable wall is then preferably a substantially shape-permanent, although possibly elastic, body sealingly adapted to the internal barrel surface and preferably of the piston type. At the front end of the barrel the needle is arranged and the invention is preferably used with containers wherein the needle axis is substantially parallel with barrel axis, and most preferably concentric therewith, resulting in that the penetration and the injection movements are substantially parallel. Within these limits and preferences a broad range of syringe type containers can be used with the present injector device, such as ampoules, cartridges, carpoules and syringes. The container need not have a separate piston rod but it is preferred that the injector mechanism can act more or less directly on the container movable wall, although it is fully possible that the container has a piston rod, in the sense of a part protruding from barrel rear end, on which the injection mechanism can act for movement of the piston, since many standardized devices are so designed. The injector can with preference be used with standard container types, e.g. as defined in DIN and ISO standards. Also usable are dual or multi chamber container types, known e.g. for preparations demanding a mixing of two or more components or precursors before administration. The components are kept separated by one or more intermediate walls of different known designs, which walls divide the barrel into several chambers, sometimes placed parallel along cartridge axis but most commonly in stacked relationship along the axis. Unification of the components may take place by breaking, penetrating or opening a valve construction in the intermediate walls. In another known design the intermediate wall or walls are of the piston type and flow communication between the chambers is accomplished by moving the piston to a by-pass section where the interior wall has one or several enlarged sections or repeated circumferential grooves and lands or piston deforming structures in a manner allowing by-flow of rear chamber content into front chamber at displacement of the rear movable wall. The chambers may contain gas, liquid or solids. Generally at least one liquid is present. Most commonly in pharmaceutical applications only two chambers are present and typically contains one liquid and one solid, the latter being dissolved and reconstituted during the mixing operation. For these types of containers it is possible both that the mixing or reconstitution step has already taken place when the container is placed in the injector or that means are provided within the device for unifying the chamber contents before the actual injection process is started.
Positional and directional statements for both the needle, container and the injector, such as xe2x80x9caxialxe2x80x9d, xe2x80x9cfrontxe2x80x9d and xe2x80x9crearxe2x80x9d, shall be understood with reference to tie needle, although when the needle and container are arranged to move together as described for syringe type containers it is equally true to refer to the above described parts of the container.
The needle may be connected to the container front in any manner, e.g. in the known manners of being permanently fixed by gluing, fusing etc. or by an attachment such as a luer connection, threads, threaded splines, snap-on connections or combinations thereof. The container front should be adapted to the attachment type selected, e.g. being of fusible material, being supplemented with a membrane that can be pierced or ruptured or having a front valve or by-pass arrangement. It is clear that the needle either may be connected by the manufacturer for best convenience or by the user prior to injection, e.g. to assure the user maintained sterility, to allow selection of needle type or gauge value or for repeated use of the device. Also in accordance with common practice the needle may be covered by a sterility preserving needle shield to be removed immediately prior to use. Use of standard needles, syringe fronts and attachments is preferred to maintain low costs. However, modifications may be used to achieve special advantages. As in the aforementioned U.S. Pat. Nos. 5,425,722 and 5,147,323 devices the needle need not be attached directly or rigidly to the container but with any other fluid connection. This e.g. in order to allow needle movement independent of the container, which may then be non-movable in the housing, and restrict movements to the needle proper in e.g. the penetration and needle retraction steps, simplifying the mechanism of the device. Unless otherwise indicated this option shall be considered included in the movable seat or carrier concept to be described. In this case the container need not be of syringe type but any container type can be used and injection performed by any pump mechanism, such as container squeezing, positive displacement pumps, e.g. piston/cylinder types, based on aspiration from the container followed by ejection, peristaltic action etc.
The injector device comprises a housing, which shall be understood in broad sense and basically as a point of reference for positional and directional statements for other parts and components. It is preferred, however, that the housing also actually enclose at least the mechanisms of the device and leave exposed mainly the parts that should be accessible to the user, mainly the control button but also auxiliary parts such as dose setting, alarm, arming, triggering and cocking controls. The container can be attached to the housing in such a manner that it remains exposed, although it is preferred that the housing also confines the container, preferably also the needle until penetration is initiated. The housing may be designed to be partially or fully openable and/or closeable to access or close its interior, which may be facilitated by any known separation or openable arrangement, e.g. threaded or hinged parts, possibly with reversible or irreversible locking means. Reversible locking may be used to access the device interior e.g. for adjustment or control or to allow simple insertion or replacement of containers, e.g. to permit reuse of the device, for loading of selected or varying preparation types or doses. As indicated it is often preferred to use the device as a disposable in which case it is preferred to factory load it with the container and a simple closure arrangement is still of value for rational assembly in manufacture. For safety and security reasons an irreversible closure may be of value to prevent any tampering with the used container and needle. In broad terms the housing shape is not critical for the basic function of the device but may influence its ergonomic and convenience properties. The overall shape of the housing can take a variety of shapes depending on among others the internal component layout. As indicated the housing incorporates at least the container and the transmission mechanism between control button and container. As in the prior art most of the mechanism parts can be arranged axially behind the container in which case a minimized housing can take an elongated form. The control button can be designed for axial depression. For the several reasons outlined it is preferred to design the control button for lateral movement relative container axis and for this option it is preferred that at least the control button is located at least partly lateral to container axis and preferably between the container ends, and preferably also at least part of the mechanism is similarly located between the control button and the container. A minimized housing embracing these parts can then be given an axially shorter but laterally wider shape and if said lateral housing, excluding button, extension is considered as xe2x80x9cheightxe2x80x9d, the axial extension as xe2x80x9clengthxe2x80x9d and the dimension perpendicular to these two as xe2x80x9cwidthxe2x80x9d, it is preferred that the maximum height to maximum width ratio is larger than 1, preferably larger than 1.5 and most preferred larger than 2. The maximum length to maximum height can often be kept less than 4, is preferably less than 3 and most preferably less than 2.5. The overall shape described has been found ergonomically suitable, structurally rigid and easy to manipulate and assemble in manufacture.
The injector further comprises a needle seat, the minimum requirement of which is to allow at least the needle, and preferably needle and container when rigidly connected, to be axially movable in relation to the housing, for penetration purposes, between a rear position and a front position, movement between which positions is used for penetration. The distance traveled between the positions should correspond at least to the desired penetration depth and, when the needle is hidden within the housing before the penetration step, also the distance needed for internal travel to expose the needle tip. The needle seat may comprise guiding structures fixed in relation to the housing, securing the desired needle path, or may alternatively or additionally comprise a carrier movable in relation to the housing and in which the needle or container is retained. Depending on the needle seat design selected the penetration mechanism to be described may act directly or indirectly on the needle, the container or the carrier for propulsion of the needle during penetration and possible needle retraction. Optionally the actual penetration depth is adjustable, e.g. in the seat path or in the penetration mechanism. Alternatively the depth is adjusted by the needle length selected.
As said the device shall incorporate arrangements for at least a needle penetration movement and an injection movement for the container content. Preferably the device also comprises arrangements for needle retraction. It is also preferred to include features assisting the user in the injection initiation steps to be described.
With some similarities to corresponding capabilities in autoinjectors, penetration and injection may take place concurrently, e.g. in simple devices or for the intentional purpose of allowing for an over depth distributed injection. Normally it is desirable to limit injection until the needle has reached or is close to its target location. This feat can be obtained with a force system acting on movable wall or piston rod for both purposes, relying for sequencing on the normally lower needle penetration resistance than fluid ejection flow resistance. Yet it is difficult to avoid at least some leakage during penetration but above all, in case the penetration movement is prevented or jams, injection will entirely fail with preparation expelled on the skin or at improper depth. Hence it is preferred to apply penetration force directly or indirectly on the needle or container, which requires some control mechanism disabling injection force application during most of the penetration phase and enabling injection force only after proper penetration. A needle retraction step can be performed manually, but is preferably made at least semi-automatically in order to guarantee safe hiding of the needle, which can be made e.g. in a manner known per se in which stored energy, typically stored during the penetration movement in a weaker return counterspring, acts to push the syringe back into the injector after completed injection. Again, this function may need a control mechanism enabling action of the return spying only after completed injection, normally accomplished by separation of the penetration and injection forces from the syringe at a certain forward extreme for the piston or piston rods freeing the return spring for action.
The penetration movement shall take place by use of manual energy applied to the control button and a penetration transmission may be needed to transfer the force between the control button and the needle, possibly via container or carrier, as the case may be, and preferably on or via the container barrel for reasons mentioned. In principle any conventional transmission means can be used, e.g. electromechanical, such as electric motors or solenoids, hydraulic, pneumatic etc. system but preferably mechanical means are utilized for simplicity. The transmission may take a variety of forms depending on the button position and mobility. If for example the button is positioned on the housing at the axial extension of the container or needle axis the transmission can be a more or less rigid connection if the button mobility is towards the front or a screw and nut transmission if the button is arranged for rotational movement around said axis. Preferably the button is arranged for movement with at least a component perpendicular to the needle axis, most preferably for needle ejection when moving the button towards the housing, e.g. as a more or less guided translational movement along such a button path or as a rotational movement around a rotation axis, preferably a rotation axis along the housing width direction in which case the push area of the button can be located behind, but preferably in front of, the rotation axis. As said the button is then most preferably positioned lateral to the needle axis but between container end boundaries. In these cases it is preferred to use a transmission able to redirect the force applied to the button, which can be done with any known such transmission arrangement, e.g. wire or belt type arrangement, a link arrangement such as a limb and joint system, a lever arrangement and preferably a wheel, preferably toothed wheel, system in which the button movement rotates the wheel for propulsion of the needle, preferably via a toothed rail. If desired any transmission may contain force transforming parts to increase, decrease or vary the force during the penetration stroke. Known such means can be used, e.g. by adaptation of gear ratios, lever degrees, knee elements or use of cam surfaces. Also the control button itself may be used for leverage, e.g. if hinged and by adaptation of pressure point to force extraction point for the transmission. Generally the penetration step requires only small forces due to the little insertion resistance in soft tissue and it is preferred for good patient control and feed-back that the button stroke length is not too short during this step. Preferably the finger movement on the button to needle movement length ratio is larger than 0.1, preferably larger than 0.2 and most preferably larger than 0.5. Preferably the ratio is less than 10, preferably less than 5 and most preferably less than 1. It is desirable that a definite stop for button movement is provided at full predetermined needle ejection, e.g. by a stop surface arranged anywhere in the chain between button and needle.
The injection movement may take place automatically during or after the penetration movement, which may serve the purpose of reducing the number of step to be performed by the patient or when injection pain is unavoidable e.g. due to irritating compounds in the injected preparation. This result will be obtained if the force application principle is used in which penetration force is applied to the container movable wall, as described, under continued operation of the control button. Alternatively non-manual stored energy may be applied to the injection mechanism, e.g. by a spring or gas pressure system, preferably to be released at the end of the penetration movement, which may require an enabling mechanism at this point similar to those used in autoinjectors, e.g. a structure on the housing releasing a lock between the stored energy drive and the movable wall at a point in the housing corresponding to completed penetration. For reasons mentioned it is preferred that also the injection movement takes place by use of manual energy since it is desirable to give the patient feedback from and control over the injection for corrective measures or speed control as pain or discomfort may result form the injection, especially at larger injected volumes. After use of the control button for penetration such manual injection may take place by use of a separate injection control, for which purpose any known injection mechanism or described transmission may be used. It is, however, preferred to use the control button also for the injection procedure. A transmission is then needed between the control button and the container movable wall, similar to that for penetration, but acting on the movable wall, and any of the transmission principles described may be used also for injection. An entirely separate transmission for the injection can be used but preferably the transmission comprises common parts for the two purposes and most preferably they differ substantially only where necessary, in particular in respect of details for shift between the phases and adaptations for each phase. In the latter regard it might be of interest to adapt the force requirements since these are higher for injection than for penetration. This can be done by increasing the gear or lever ratio. Preferably the finger movement on the button to movable wall movement length ratio is larger than that for finger movement versus needle movement used under penetration. For injection said ratio is preferably greater than 0.2, preferably larger than 0.5 and most preferably larger than 1. Preferably the ratio is less than 20, preferably less than 10 and most preferably less than 5. In case the finger movement tends to be inconveniently long it is possible and preferred to allow for repeated operation of the control button until emptying of the container is complete.
For the simplest operational options described, e.g. when acting on the container movable wall and when using a single button stroke for both phases, it might not be necessary to include any switch system for enabling and disabling respectively or redirecting the forces applied to the control button. To reach most of the preferred capabilities described, however, it is preferred to includes such a switch system. A first desired switch function is a phase shift system allowing the force applied to first act on the needle, directly or indirectly e.g. via container barrel or a carrier, for penetration and then act, directly or indirectly, on the movable wall for injection. A second desired switch function is a reconnect system allowing repeated operations of the control button. These desired functions are to some extent mutually dependent, as for example press and release actions on the button can be used to accomplish a phase shift, e.g. at a certain position for the button movement although it is preferred to use other means than the button, and all possibilities and combinations cannot be enumerated of described in detail. In broad terms phase shift can preferably be made at a certain relative axial location between needle and housing, e.g. corresponding to completed penetration stroke or preferably slightly before to avoid too high tolerance demands on the shift mechanism. Physically the shift can preferably be made by using a structure, with substantially fixed location with respect to the housing, to redirect or unlock the force applied for action on the movable wall, e.g by deflection, rotation or any other mechanism, or preferably by applying force at a constant location, preferably by a wheel, where automatic shift takes place when penetration a movement is completed, e.g. by having the wheel first act on a surface for penetration and then changing over to a surface for injection when penetration is completed, which principle also allows for change of gear ratio. For several reasons, e.g. to secure proper sequencing and avoid inadvertent withdrawal, to facilitate adaptations for later needle retraction and to indicate penetration completion to the user, it is preferred to provide a lock to hold, at least temporary, the needle in the front position, which can be made by any lock structure, e.g. a hook structure, preferably biased for automatic engagement in that position and possibly designed for, or supplemented with, a tactile or audible confirmation of penetration completion. The lock may be permanent, e.g. if no needle return function is present, or releasable with features of the internal mechanism or even manually if used for needle or container front access.
A properly designed phase shirt system, preferably by structures other than the button, as above offers broad freedom for design of the reconnect system and movement pattern for the control button. It is possible to use a single button stroke for both penetration and injection, e.g. to minimize patient actions or for small injection volumes or penetration depths or to allow for aspiration of liquid and in this case no reconnect system need to be present. Among others in order to give the patient phase dependent feedback, arrange for phase dependent adaptations or avoid too long button strokes, it is, however, preferred to use at least two actions on the button, preferably at least one for penetration and at least one for injection, and possibly several strokes within a phase, especially the injection phase as said. This can be accomplished by using the button as part of the phase shift system, e.g. by using the end of the first button stroke for phase shift and further movement of the button for injection. It is preferred, however, to use the phase system principles mentioned other than the button, which permits a more general design of the reconnect system. A general reconnect system may allow two-way button movement. It may allow force to be applied to the transmission during movement in both directions but is preferably designed to be idle in one movement direction, preferably idle when moved away from the housing, for best convenience. Mechanically any known one or two way means may be used, such as clutch, centrifugal or friction based mechanisms, pawl and ratchet mechanisms or preferably a wheel with releasable axis. With any such design the button movements can be repeated freely, e.g. allowing patient mistakes or action individuality, while the phase shift system secures the proper phase sequencing. Reversible phase action is possible. It is for example beneficial that the needle movement during penetration can be reversed in certain situations, e.g. to allow interruption and selection of new injection site if pain is experienced or to allow exposure of the needle or container front for inspection or for needle attachment. Reversible penetration can be obtained e.g. by having a force bias in the needle reverse direction, e.g. a needle retraction spring. During injection a several stroke pumping action is automatically achieved with the general reconnect system, more safely though if rearward movement of the container is prevented, e.g. in the embodiments with fixed container, if not rearward biased or if locked in the foremost position as described. As an additional safety measure during the injection, especially when several stokes are needed, rearward movement of the movable wall can be prevented, e.g. by allowing forward movement only of the parts acting on the movable wall, e.g. by inclusion of a friction element, a one-way ratchet mechanism or by similar means. It is also preferred to bias the button itself towards one of its positions, preferably towards the button start position such as the outer distal position relative the housing, which can be done with simple and inexpensive means, such as a spring in metal, elastomer or plastic.
For reasons stated a needle return function is preferably included in the injector. With respect to force application for needle retraction similar considerations apply as for penetration, i.e. the force can be applied directly to the needle or its attachment, to container barrel or any carrier for these parts. The needle may be retracted by application of manual energy, e.g. to give the user control also over this action. A separate control may then be arranged, allowing a simple construction and a simple connection between control and needle. For convenience it is preferred to use the control button also for needle retraction, especially if this step shall take place in connection with the injection procedure and for withdrawal from the tissue. A transmission and button reconnect system of principles similar to that for penetration and injection may then be needed. Needle withdrawal from the tissue is rarely a painful task, however, that necessarily need full manual control. For this and other reasons it is preferred make needle retraction at least partially automatic. The function may be semi-automatic in the sense that after a mandatory manual triggering needle retraction proceeds automatically, preferably by release of stored energy, e.g. in the known manner of arranging a return spring biased for rearward needle movement, commonly compressed during the needle penetration step The triggering may take place via a separate control for this purpose but preferably the control button is also used as trigger for needle retraction. The control button may release the needle retraction when it is released after the injection but it is preferred that an additional, repeated, operation of the button is used. For highest safety and ease of operation needle retraction can be fully automatic in the sense that this step follows at a particular point in the injection procedure, without any manual triggering action from the user. The procedure point is preferably when the expulsion of preparation is finished and hence the injection phase completed, which may be when the movable wall bottoms out, in case of container complete emptying, or at a certain movable wall position, in case of partial emptying, the latter useful mainly when the dose can be set or adjusted or for repeated injections from multi-dose containers. Expressed in another way, the movable wall arrival at the predetermined position is taken as the triggering event for needle retraction. Mechanically any part of the injection transmission including the button, which parts has a determined positional relationship to movable wall position, can be used as internal trigger, e.g. to enable release of stored energy for example by unlocking a return spring lock. In case a lock is provided to retain the needle position after penetration, in the preferred manner described earlier, with preference such a lock can be used for enabling of a return spring for action. In case it is desirable to disable the device permanently after needle retraction, e.g. for single use disposable devices, arrangements may be provided to lock the needle in the retracted position in a non-releasable manner, e.g. by any known means, again anywhere in the transmission chain. As part of this feature, or additionally e.g. to indicate the used status to the user, the control button can be locked against further movements, preferably in its compressed position to conserve space. In case no needle retraction function is present, but other safety precautions are relied on, e.g. incineration, for destruction the non-releasable locking can take place after the injection phase.
In order to allow setting of the dose to be ejected, e.g. for partial or repeated injection, a dose setting mechanism can be included. Since the dose setting generally takes place before the actual injection procedure is initiated and without restrictions in device position, controls for this purpose can be arranged more freely than the control button. Although it is possible to include adjustable displacement limitations acting on the movable wall as such, it is generally preferred to provide such limitations for action on the parts earlier in the injection chain. They may be arranged in the control button or anywhere in the injection transmission, but it is preferred to provide separate such limitations. Any common means, known as such in for example injection pens, can be used. If the last part of the transmission affecting the movable wall or the piston rod as the case may be, is regarded as a xe2x80x9cplungerxe2x80x9d arrangement it is for example possible to use an adjustable stop surface for the plunger arrangement, an adjustable space for plunger dead run relative to the movable wall or a combination thereof. It is possible that the injection stroke length, or combined stroke lengths, for the control button varies for different dose settings but preferably dose setting mechanisms are selected in which the stroke lengths are kept constant and independent of the dose setting.
It is also preferred to include in the device features facilitating initiation steps preceding the actual injection. It is possible to deliver the device without any container or needle for later attachment of these parts and in order to facilitate attachment the container site may comprise an attachment such as a push lock, bayonet, threads or any other fit. It is also possible that the needle is pre-mounted on the container but commonly it need to be connected immediately prior to use or allow for replacements and in most cases a needle shield need to be removed prior to use and in all these instances the needle attachment site, most often the container front, need to be accessible to the user. Possibly the device has a compartment for needle storage before attachment. In case of dual or multiple chamber cartridges initiation may require an initial movement of the movable wall to unify and mix chamber contents and although this step may be performed before container attachment to the device it is preferred to allow for this when attached to the device, e.g. allowing the plunger arrangement to be initially movable against the movable wall, e.g. by a temporary release from the transmission, but preferably by making the container axially movable against the plunger when stationary in the housing and most preferably by threaded attachment permitting cautious displacement of the movable wall as described e.g. in U.S. Pat. No. 4,968,299. An initial displacement of the movable wall is also needed to perform de-aeration and pre-ejection, which movement may take place with similar means as for multiple chamber containers. Any initial movement of the movable wall may require high break-loose forces. For any or all of these actions it is beneficial that at least the container front is accessible to the user, which can be arranged for by utilization of the penetration mechanism to at least partially make the penetration movement and preferably temporary lock this position to resist the manipulation steps applied. It is also possible and often preferred to make at least the device front part open or openable through removal, hinged door etc. The displacement of the movable wall for the above mentioned initiation purposes may take place by manually pushing the plunger or the container towards each other in axial direction. It is, however, preferred to arrange for an assisting leverage or gear ratio, for example to increase force for break-loose, reduce speed in mixing or keep the initiation movement short in de-aeration and pre-ejection. Any known leverage principle can be used but a preferred arrangement is use a hinged door for the device front, the closing of which causes the container to move rearwards, preferably under force amplification and preferably under displacement of the movable wall forwards, such as when the wall is substantially stationary in relation to the housing. After closing of the door the needle is preferably hidden within the housing and it may be beneficial to arrange the door so that it cannot be at least fully closed unless the needle is properly attached and further so that the door is permanently and irreversibly locked, and possibly also arranged to block any further change of a dose setting control if present. A door may additionally serve to influence the possible control button movements, in particular to enable or disable movement thereof. For example the button may be inoperable until the door has been fully closed, with any of the additional functions mentioned above, either by being disconnected from the transmission or by being held stationary in a given position by blockage of the button or the transmission. All these arrangements serve to secure a proper sequence of actions and reduce the risks for mistakes or misuse.
The methods for using the device follows from the descriptions made of structures, functions and objects. Below a summary of preferred actions. Any door or closure over the device front is removed or opened. If the container is not pre-assembled in the device housing the operator inserts the container and possibly connects it to attachments provided. If the container is a dual or multiple chamber device mixing operation may be undertaken before attachment to the device but is preferably made when attached or during attachment to the device, preferably by actions involving an axial displacement of the container towards a plunger arrangement in rest abutting the movable wall. Unless a needle is already in place the operator mounts a needle on its seat and possibly removes any needle shield present. The needle is pointed roughly upwards and the movable wall is moved forward to expel air and possibly eject a small preparation amount to assure proper function. Preferably the wall is moved forward by displacing the container rearwards against a plunger arrangement and most preferably by closing a hinged door arranged to also displace the container rearwards. Such displacement may be levered so that the closing length exceeds the container displacement length. Preferably the closing also acts to enable the control button for action. The steps performed should secure that the needle is now hidden within the device. If applicable a dose setting operation may take place at any point up to now. The control button is operated to perform penetration movement to bring the needle to an exposed position. This is preferably made in a single step, without repeated action on the button, and preferably by pressing the button towards the housing, a movement preferably having at least a component perpendicular to the axial direction. The exposed needle may now be inserted into a target object, e.g. human or animal tissue or any other material or device e.g. for laboratory use, but preferably the device front is placed against the receiving object beforehand so that said insertion takes place as a result of the penetration movement. Preferably the needle or container is locked at the penetration end position and it is preferred that an audible or tactile signal is issued, by the locking arrangement or otherwise, to confirm completed penetration to the user. A injection step may now be performed. This can be done with a continued movement of the control button but preferably the button movement pattern is changed for injection, preferably involving release for return to a start position and most preferably so that a new movement from the start position performs the injection. Several injection strokes can be made with the button during injection, especially for larger injected volumes or as an adaptation for weak persons. Completed injection may be sensed as a stop for the button when the movable wall reaches the container end or at abutment of stop surfaces arranged in the transmission. Preferably a needle return step is now performed, either automatically or triggered by the operator. Triggering may be made by a separate trigger, by release of the control button or first when the button is again operated. Although the needle may be removed from the object before the needle return step it is preferred that removal takes place as a result of the needle retraction step.
Although the above method steps have been described as a sequence of given order it is within the spirit of the invention that other sequence orders may be used unless specific statements to the contrary are given.